A comparison of the Michaelis–Menten and HCH‐1 models

Brown, Russell F.; Holtzapple, Mark T.

doi:10.1002/bit.260361110

Cited by 12 publications

(6 citation statements)

References 13 publications

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“…shrinking site hydrolysis model with Langmuir-type adsorption isotherm (Humphrey, 1979;Movagharnejad et al, 2003) (Holtzapple et al, 1984;Brown and Holtzapple et al, 1990) • Resistances offered by the crystallinity and composition variation with respect to the degree of hydrolysis were neglected, as these studies were carried out on noncrystalline cellulose.…”

Section: Independent Inhibition Studies With Reactionmentioning

confidence: 99%

Modeling Intrinsic Kinetics of Enzymatic Cellulose Hydrolysis

Peri

Karra

Lee

et al. 2008

Biotechnol Progress

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A multistep approach was taken to investigate the intrinsic kinetics of the cellulase enzyme complex as observed with hydrolysis of noncrystalline cellulose (NCC). In the first stage, published initial rate mechanistic models were built and critically evaluated for their performance in predicting time-course kinetics, using the data obtained from enzymatic hydrolysis experiments performed on two substrates: NCC and alpha-cellulose. In the second stage, assessment of the effect of reaction intermediates and products on intrinsic kinetics of enzymatic hydrolysis was performed using NCC hydrolysis experiments, isolating external factors such as mass transfer effects, physical properties of substrate, etc. In the final stage, a comprehensive intrinsic kinetics mechanism was proposed. From batch experiments using NCC, the time-course data on cellulose, cello-oligosaccharides (COS), cellobiose, and glucose were taken and used to estimate the parameters in the kinetic model. The model predictions of NCC, COS, cellobiose, and glucose profiles show a good agreement with experimental data generated from hydrolysis of different initial compositions of substrate (NCC supplemented with COS, cellobiose, and glucose). Finally, sensitivity analysis was performed on each model parameter; this analysis provides some insights into the yield of glucose in the enzymatic hydrolysis. The proposed intrinsic kinetic model parametrized for dilute cellulose systems forms a basis for modeling the complex enzymatic kinetics of cellulose hydrolysis in the presence of limiting factors offered by substrate and enzyme characteristics.

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Section: Independent Inhibition Studies With Reactionmentioning

confidence: 99%

Modeling Intrinsic Kinetics of Enzymatic Cellulose Hydrolysis

Peri

Karra

Lee

et al. 2008

Biotechnol Progress

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“…A similar breakthrough for surface-active enzymes is missing. There is no canonical kinetic description although specific models [3][4][5][6][7][8] and conceptual treatments [9][10][11] have been put forward. It is only consequent that even recent authoritative treatments on enzyme kinetics [12] shy away from discussing interfacial catalysis or do so only with a focus on special systems like membrane surfaces [13,Section 7.12].…”

Section: Introductionmentioning

confidence: 99%

A generic rate law for surface‐active enzymes

Kartal

Ebenhöh

2013

FEBS Letters

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a b s t r a c tMany biochemical reactions are confined to interfaces, such as membranes or cell walls. Despite their importance, no canonical rate laws describing the kinetics of surface-active enzymes exist. Combining the approach chosen by Michaelis and Menten 100 years ago with concepts from surface chemical physics, we here present an approach to derive generic rate laws of enzymatic processes at surfaces. We illustrate this by a simple reversible conversion on a surface to stress key differences to the classical case in solution. The available area function, a concept from surface physics which enters the rate law, covers different models of adsorption and presents a unifying perspective on saturation effects and competition between enzymes. A remarkable implication is the direct dependence of the rate of a given enzyme on all other enzymatic species able to bind at the surface. The generic approach highlights general principles of the kinetics of surface-active enzymes and allows to build consistent mathematical models of more complex pathways involving reactions at interfaces.

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“…This process has received rapidly increasing research interest, as it is important both in natural carbon cycling (and hence the balance between soil organic matter and atmospheric carbon) and in emerging industries that produce sustainable fuels and materials from lignocellulosic feedstocks . Many reports have used a conventional or slightly adapted Michaelis–Menten (MM) approach to analyze initial rates for cellulases acting on insoluble cellulose, − but a number of concerns regarding this practice have been raised. ,, The main caveat, which was emphasized already in the aforementioned review by McLaren and Packer, is whether the substrate is in excess with respect to the enzyme under typical experimental conditions. This is a fundamental requirement for the QSSA, but its validity is difficult to assess in heterogeneous systems, where a molar concentration of substrate cannot be defined unambiguously.…”

mentioning

confidence: 99%

An Inverse Michaelis–Menten Approach for Interfacial Enzyme Kinetics

2017

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Interfacial enzyme reactions are ubiquitous both in vivo and in technical applications, but analysis of their kinetics remains controversial. In particular, it is unclear whether conventional Michaelis–Menten theory, which requires a large excess of substrate, can be applied. Here, an extensive experimental study of the enzymatic hydrolysis of insoluble cellulose indeed showed that the conventional approach had a limited applicability. Instead we argue that, unlike bulk reactions, interfacial enzyme catalysis may reach a steady-state condition in the opposite experimental limit, where the concentration of enzyme far exceeded the molar concentration of accessible surface sites. Under this condition, an “inverse Michaelis–Menten equation”, where the roles of enzyme and substrate had been swapped, proved to be readily applicable. We suggest that this inverted approach provides a general tool for kinetic analyses of interfacial enzyme reactions and that its analogy to established theory provides a bridge to the accumulated understanding of steady-state enzyme kinetics. Finally, we show that the ratio of parameters from conventional and inverted Michaelis–Menten analysis reveals the density of enzyme attack sites on the substrate surface as probed by one specific enzyme. This density, which is an analogue to a molar substrate concentration for interfacial reactions, was shown to vary strongly even among related enzymes. This difference reflects how the enzyme discriminates between local differences in surface structure on the substrate.

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A comparison of the Michaelis–Menten and HCH‐1 models

Cited by 12 publications

References 13 publications

Modeling Intrinsic Kinetics of Enzymatic Cellulose Hydrolysis

Modeling Intrinsic Kinetics of Enzymatic Cellulose Hydrolysis

A generic rate law for surface‐active enzymes

An Inverse Michaelis–Menten Approach for Interfacial Enzyme Kinetics

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